1. Field of the Invention
The present invention relates to a seal ring and connection joint for conduits, pressure vessels or the like.
2. Description of Related Art
When connecting adjacent sections of fluid flow conduits or vessels, seal rings are typically interposed at the interface of adjacent connecting flanged conduits or vessel portions which are then bolted or clamped together. The seal ring is typically metallic, the seal being affected by elastic or plastic deformation of a sealing lip of the seal ring against a sealing surface.
Most known seal rings and joints work, to a greater or lesser extent, when the pressure within the conduit, pressure vessel or the like is considerably greater than the ambient pressure outside of the conduit, pressure vessel or the like i.e. the seal or joint is pressure energized. They do, however, work less satisfactorily when the internal and external pressures are similar or, even, when the external pressure is greater than the internal pressure, i.e. the seal is not pressure energized.
US2001045709 discloses a seal ring and associated connection joint. US2001045709 discloses an annular seal ring comprising an inner integrally formed sealing portion, an outer integrally formed sealing portion, and an interconnecting web portion. The inner sealing portion comprises a pair of annular seal lips facing the outer sealing portion and extends in a transverse direction to said web portion, wherein the outer seal portion comprises a pair of annular seal lips facing the inner seal portion and extends in a transverse direction to said web portion. The web portion extends radially between the pair of seal lips on the inner seal portion and the pair of seal lips on the outer seal portion, and each respective seal lip is arranged to project transversely from said web portion by a distance which is substantially greater than the thickness of said web portion in a direction substantially perpendicular to the radial direction. US2001045709 also discloses a conduit joint comprising a seal ring interposed at an interface between a pair of conduits or vessel defining members, wherein the conduits or vessel defining members are provided at the interface with respective recessed portions, complementarily shaped and dimensioned to receive respective portions of the inner and outer annular seal ring. A first inner recessed portion comprises a radially outer surface sloped away from the interface in an inwardly radial direction, and a second of the recessed portions comprises a radially inner surface sloping away from the interface in an outwardly radial direction.
According to US2001045709 it is preferred that the dimensions of the inner and outer sealing portions 5, 9 of seal ring 4 are substantially similar to each other. This results in the inner and outer sealing portions undergoing substantially equal amounts of deformation on tightening of the joint. This preference was based on the assumption that if the dimensions of one sealing portion were significantly larger than those of the other, it would necessarily result in the sealing portion of lesser dimensions undergoing higher deformation and likely to fracture on tightening of the joint.